Ok besides the Alt gauge and the Oil gauge There are three more wires coming off the C5TB10A665E wiring harness. What are the other three wires for?

 

C5TZ-10A665-C .. Instrument Cluster Wiring Harness-Use with Oil & Amp Warning Lamps in conjunction with optional Oil & Amp Gauges / Marked: C5TB-10A665-A or B or E / Obsolete

Applications: 1965/66 F100/250 2WD 240/300/352 - 1966 F100 4WD 240/300/352.

 

Your truck is a '64, right? But the harness you reference is '65 - '66, right? Just checking. I can't tell by the harness part number you reference, but I do have a '66 wiring diagram, so if you will post the colors of the three wires you are asking about, maybe I can help that way. It's worth a try.

 

SuperSabre, normally when I post about specific items, rarely does it have to do with my truck. I acquire so many parts, I remove a lot of parts and most times I label all the parts. Every once in awhile something gets away from me that wasn't labeled so I need to identify it before passing it on, selling it or trading. Never the less, I always try to be as accurate as possible with my dealings. I'll get the colors or markings off of what I have.

 

I was just re-taping my harness. My guess is that the 3 wires are for oil light, alternator light and cigar lighter. Those were 'extra' on mine. There is a separate harness that covers the optional guages for Oil and Alt.

 

Oil & Amp Warning Lamps were standard equipment, Oil & Amp Gauges were optional.

The wire for the lighter is separate, it's not part of any wiring harness.

 

This is the harness for the oil and Alt. I found out one is ground, one taps into the lights on the main harness and the other not sure yet but it also taps into main harness via spade connection.